Non-attendance at diabetic eye screening and risk of sight-threatening diabetic retinopathy: a population-based cohort study

AIMS/HYPOTHESIS

This study evaluated whether repeated non-attendance for diabetic eye screening is associated with the risk of sight-threatening diabetic retinopathy (STDR).

METHODS

This was a cohort study of 6,556 residents with diabetes who were invited for screening between 2008 and 2011 in a population-based eye screening programme in inner London and who attended for their first-ever screen in 2008. The proportion of participants with STDR was evaluated in relation to the number of years in which screening was missed.

RESULTS

The proportion of participants who did not attend screening decreased between 2009 and 2011 (annual reduction 1.6% [95% CI 0.9%, 2.3%]). The adjusted relative odds of STDR for 210 participants who did not attend two consecutive years of screening were 3.76 (95% CI 2.14, 6.61; p < 0.001), compared with participants who were screened annually. In 605 participants with mild non-proliferative retinopathy at the first screen, the adjusted relative odds of developing proliferative or moderate to severe non-proliferative retinopathy were 5.72 (95% CI 7.43, 22.83; p = 0.013) for 53 participants who missed two screens.

CONCLUSIONS/INTERPRETATION

Patients who do not attend diabetic eye screening are at increased risk of developing STDR. Tracing of non-attenders with evidence of established retinopathy should be an important fail-safe procedure.

Changes in detection of retinopathy in type 2 diabetes in the first 4 years of a population-based diabetic eye screening program: retrospective cohort study

OBJECTIVE

Annual diabetic eye screening has been implemented in England since 2008. This study aimed to estimate changes in the detection of retinopathy in the first 4 years of the program.

RESEARCH DESIGN AND METHODS

Participants included 32,340 patients with type 2 diabetes resident in three London boroughs with one or more screening records between 2008 and 2011. Data for 87,570 digital images from 2008 to 2011 were analyzed. Frequency of sight-threatening diabetic retinopathy (STDR) was estimated by year of screen for first screens and for subsequent screens according to retinopathy status at first screen.

RESULTS

Among 16,621 first-ever screens, the frequency of STDR was 7.1% in 2008, declining to 6.4% in 2011 (P = 0.087). The proportion with a duration of diabetes of <1 year at first screen increased from 18.7% in 2008 to 48.6% in 2011. Second or later screens were received by 26,308 participants. In participants with mild nonproliferative retinopathy at first screen, the proportion with STDR at second or later screen declined from 21.6% in 2008 to 8.4% in 2011 (annual change -2.2% [95% CI -3.3 to -1.0], P < 0.001). In participants with no retinopathy at first screen, STDR declined from 9.2% in 2008 to 3.2% in 2011 (annual change -1.8% [-2.0 to -1.7], P < 0.001). Declining trends were similar in sociodemographic subgroups.

CONCLUSIONS

After the inception of population-based diabetic eye screening, patients at lower risk of STDR contribute an increasing proportion to the eligible population, and the proportion detected with STDR at second or subsequent screening rounds declines rapidly.

Recent HbA1c values and mortality risk in type 2 diabetes. population-based case-control study

This study aimed to evaluate mortality within 365 days of HbA1c values of <6.5% or >9.0% in participants with clinical type 2 diabetes mellitus. A matched nested case-control study was implemented, within a cohort of participants with type 2 diabetes from 2000 to 2008. Conditional logistic regression was used to model the odds ratio for mortality adjusting for comorbidity and drug utilisation. There were 97,450 participants with type 2 diabetes; 16,585 cases that died during follow up were matched to 16,585 controls. The most recent HbA1c value was <6.5% (48 mmol/mol) for 22.2% of cases and 24.2% of controls, the HbA1c was >9.0% for 9.0% of cases and 7.7% of controls. In a complete case analysis, the adjusted odds ratio (AOR) for mortality associated with most recent HbA1c <6.5% was 1.31 (95% confidence interval (CI): 1.21,1.42). After multiple imputation of missing HbA1c values the AOR was 1.20 (CI: 1.12,1.28). The complete case analysis gave an AOR for HbA1c >9.0% of 1.51 (CI: 1.33, 1.70), in the multiple imputation analysis this was 1.29 (1.17,1.41). The risk associated with HbA1c <6.5% was age dependent. In the multiple imputation analysis the AOR was 1.53 (CI: 0.84 to 2.79) at age<55 years but 1.04 (CI: 0.92, 1.17) at age 85 years and over. In non-randomised data, values of HbA1c that are either <6.5% or >9.0% may be associated with increased mortality within one year in clinical type 2 diabetes. Relative risks may be higher at younger ages.

Prevalence of depression and utilization of health care in single and multiple morbidity: a population-based cohort study

BACKGROUND

This study aimed to determine whether depression in patients with long-term conditions is associated with the number of morbidities or the type of co-morbidity. Method A cohort study of 299 912 participants aged 30-100 years. The prevalence of depression, rates of health-care utilization and costs were evaluated in relation to diagnoses of diabetes mellitus (DM), coronary heart disease (CHD), stroke and colorectal cancer.

RESULTS

The age-standardized prevalence of depression was 7% in men and 14% in women with no morbidity. The frequency of depression increased in single morbidities including DM (men 13%, women 22%), CHD (men 15%, women 24%), stroke (men 14%, women 26%) or colorectal cancer (men 10%, women 21%). Participants with concurrent diabetes, CHD and stroke had a very high prevalence of depression (men 23%, women 49%). The relative rate of depression for one morbidity was 1.63 [95% confidence interval (CI) 1.59-1.66], two morbidities 1.96 (95% CI 1.89-2.03) and three morbidities 2.35 (95% CI 2.03-2.59). Compared to those with no morbidity, depression was associated with higher rates of health-care utilization and increased costs at any level of morbidity. In women aged 55 to 64 years without morbidity, the mean annual health-care cost was £513 without depression and £1074 with depression; when three morbidities were present, the cost was £1495 without depression and £2878 with depression.

CONCLUSIONS

Depression prevalence and health-care costs are more strongly associated with the number of morbidities than the nature of the co-morbid diagnosis.

Cardiovascular risk factors and cognitive decline in adults aged 50 and over: a population-based cohort study

OBJECTIVES

the objective of the present study was to explore the association between cardiovascular risk and cognitive decline in adults aged 50 and over.

METHODS

participants were older adults who participated in the English Longitudinal Study of Ageing. Outcome measures included standardised z-scores for global cognition, memory and executive functioning. Associations between cardiovascular risk factors and 10-year Framingham risk scores with cognitive outcomes at 4-year and 8-year follow-ups were estimated.

RESULTS

the mean age of participants (n = 8,780) at 2004-05 survey was 66.93 and 55% were females. Participants in the highest quartile of Framingham stroke risk score (FSR) had lower global cognition (b = -0.73,CI: -1.37, -0.10), memory (b = -0.56, CI: -0.99, -0.12) and executive (b = -0.37, CI: -0.74, -0.01) scores at 4-year follow-up compared with those in the lower quartile. Systolic blood pressure ≥160 mmHg at 1998-2001 survey was associated with lower global cognitive (b = -1.26, CI: -2.52, -0.01) and specific memory (b = -1.16, CI: -1.94, -0.37) scores at 8-year follow-up. Smoking was consistently associated with lower performance on all three cognitive outcomes.

CONCLUSION

elevated cardiovascular risk may be associated with accelerated decline in cognitive functioning in the elderly. Future intervention studies may be better focused on overall risk rather than individual risk factor levels.

Epidemiology of clinical body mass index recording in an obese population in primary care: a cohort study

BACKGROUND

Protecting and promoting the health of obese people is an important public health concern. This study evaluated the recording of body mass index and medical diagnostic codes for obesity in obese patients in UK primary care.

METHODS

A cohort study was implemented in the UK General Practice Research Database. Subjects were aged 18-100 years and were diagnosed with obesity between 1997 and 2007. The frequency of obesity monitoring was evaluated.

RESULTS

There were 67 000 obese patients at 127 family practices. The proportion of obese patients with no annual body mass index (BMI) record reached 65% of men and 63% of women in 2000, declining to 55 and 48% in 2009. Medical diagnostic codes for obesity were infrequently recorded. The mean BMI of obese patients increased to 35.5 kg/m(2) [95% confidence interval (CI): 35.4-35.7] in men and 37.0 kg/m(2) (95% CI: 36.9-37.1) in women by 2009. In 2009, 37% of obese men with BMI records, and 39% of women, showed a BMI increase of ≥1 kg/m(2) since the previous reading.

CONCLUSIONS

Obese patients do not have BMI values recorded regularly. The mean BMI of obese patients, and the proportion gaining weight over time, is increasing. Improved strategies for monitoring and managing obesity are required.

Ethnic variation in the prevalence of visual impairment in people attending diabetic retinopathy screening in the United Kingdom (DRIVE UK)

Purpose

To provide estimates of visual impairment in people with diabetes attending screening in a multi-ethnic population in England (United Kingdom).

Methods

The Diabetic Retinopathy In Various Ethnic groups in UK (DRIVE UK) Study is a cross-sectional study on the ethnic variations of the prevalence of DR and visual impairment in two multi-racial cohorts in the UK. People on the diabetes register in West Yorkshire and South East London who were screened, treated or monitored between April 2008 to July 2009 (London) or August 2009 (West Yorkshire) were included in the study. Data on age, gender, ethnic group, visual acuity and diabetic retinopathy were collected. Ethnic group was defined according to the 2011 census classification. The two main ethnic minority groups represented here are Blacks (“Black/African/Caribbean/Black British”) and South Asians (“Asians originating from the Indian subcontinent”). We examined the prevalence of visual impairment in the better eye using three cut-off points (a) loss of vision sufficient for driving (approximately <6/9) (b) visual impairment (<6/12) and (c) severe visual impairment (<6/60), standardising the prevalence of visual impairment in the minority ethnic groups to the age-structure of the white population.

Results

Data on visual acuity and were available on 50,331individuals 3.4% of people diagnosed with diabetes and attending screening were visually impaired (95% confidence intervals (CI) 3.2% to 3.5%) and 0.39% severely visually impaired (0.33% to 0.44%). Blacks and South Asians had a higher prevalence of visual impairment (directly age standardised prevalence 4.6%, 95% CI 4.0% to 5.1% and 6.9%, 95% CI 5.8% to 8.0% respectively) compared to white people (3.3%, 95% CI 3.1% to 3.5%). Visual loss was also more prevalent with increasing age, type 1 diabetes and in people living in Yorkshire.

Conclusions

Visual impairment remains an important public health problem in people with diabetes, and is more prevalent in the minority ethnic groups in the UK.

Trends in antiepileptic drug utilisation in UK primary care 1993-2008: cohort study using the General Practice Research Database

PURPOSE

To describe changes in utilisation of antiepileptic drugs (AED) by people with epilepsy in the United Kingdom during 1993-2008.

METHODS

Cohort study of 63,586 participants with epilepsy and prescribed AEDs from 434 UK family practices. Prescriptions for different AEDs and AED combinations were evaluated by calendar year, gender and age group.

RESULTS

Total follow-up was 361,207 person-years, with 282,080 person-years treated with AEDs and 79,126 person-years untreated. AED monotherapy accounted for 72.6% of treated person years of follow-up. Carbamazepine and valproates were among the most commonly used medications throughout 1993-2008. Phenytoin accounted for 39.5% of treated person-years in 1993 declining to 18.3% by 2008. Use of barbiturates declined from 14.3% in 1993 to 6.0% in 2008. In contrast between 1993 and 2008 there were substantial increases in the use of lamotrigine (2.0% to 17.0%) and to a lesser extent levetiracetam (0% to 8.6%). Newer AEDs were more frequently prescribed to younger participants, especially women aged 15-44 years, while older adults were more likely to be prescribed longer established AEDs. In 1993, 201 different AED combinations were prescribed, increasing to 500 different combinations in 2008. Combinations of sodium valproate and carbamazepine were frequent throughout, while sodium valproate and lamotrigine was frequent in 2008.

CONCLUSIONS

Utilisation of newer AEDs in UK primary care has increased between 1993 and 2008 with increasing use of diverse combinations of AEDs. The data quantify exposure to AEDs relevant to planning analytical pharmaco-epidemiological studies, as well as providing information to inform prescribing policies.

Incidence, mortality, and disease associations of pyoderma gangrenosum in the United Kingdom: a retrospective cohort study

Pyoderma gangrenosum (PG) is an important disease with significant complications. The objectives of this study were to determine incidence and mortality of PG and strength of reported associations. A retrospective cohort study was completed using computerized medical records from the General Practice Research Database, a large representative UK database. Patients with PG and three groups of age-, sex-, and practice-matched controls--general population, rheumatoid arthritis (RA), and inflammatory bowel disease (IBD) controls--were included in the study. Incidence and mortality were determined and validation undertaken to inform diagnostic accuracy. In all there were 313 people with the median age of 59 (interquartile range 41-72) years, and of them 185 (59%) were female. The adjusted incidence rate standardized to European standard population was 0.63 (95% confidence interval (CI) 0.57-0.71) per 100,000 person-years. The risk of death was three times higher than that for general controls (adjusted hazard ratio=3.03, 95% CI 1.84-4.73, P<0.001), 72% higher than that for IBD controls (adjusted hazard ratio=1.72, 95% CI 1.17-2.59, P=0.013), with a borderline increase compared with RA controls (adjusted hazard ratio=1.55, 95% CI 1.01-2.37, P=0.045). Disease associations were present in 110 (33%) participants: IBD, n=67 (20.2%); RA, n=39 (11.8%); and hematological disorders, n=13 (3.9%). To our knowledge, there are no previous population-based studies of the epidemiology of PG, an important disease with significantly increased mortality.

Is illicit drug use harmful to cognitive functioning in the midadult years? A cohort-based investigation

From March to July of 2011, the authors investigated the prospective association between illicit drug use and cognitive functioning during the midadult years. A total of 8,992 participants who were surveyed at 42 years of age in the National Child Development Study (1999-2000) were included. The authors analyzed data on 3 cognitive functioning measures (memory index, executive functioning index, and overall cognitive index) when the participants were 50 years of age (2008-2009). Illicit drug use at 42 years of age was based on self-reported current or past use of any of 12 illicit drugs. Multivariable regression analyses were performed to estimate the association between different illicit drug use measures at 42 years of age and cognitive functioning at 50 years of age. A positive association was observed between ever (past or current) illicit drug use and cognitive functioning (β = 0.62, P < 0.001), although the effect size was small. Even though there was no clear evidence against the null hypothesis, drug dependence (β = -0.27, P = 0.58) and long-term illicit drug use (β = -0.04, P = 0.87) tended to be negatively associated with cognitive functioning. At the population level, it does not appear that current illicit drug use is associated with impaired cognitive functioning in early middle age. However, the authors cannot exclude the possibility that some individuals and groups, such as those with heavier or more prolonged use, could be harmed.

Coding, recording and incidence of different forms of coronary heart disease in primary care

Objectives

To evaluate the coding, recording and incidence of coronary heart disease (CHD) in primary care electronic medical records.

Methods

Data were drawn from the UK General Practice Research Database. Analyses evaluated the occurrence of 271 READ medical diagnostic codes, including categories for ‘Angina’, ‘Myocardial Infarction’, ‘Coronary Artery Bypass Grafting’ (CABG), ‘percutaneous transluminal coronary angioplasty’ (PCTA) and ‘Other Coronary Heart Disease’. Time-to-event analyses were implemented to evaluate occurrences of different groups of codes after the index date.

Results

Among 300,020 participants aged greater than 30 years there were 75,197 unique occurrences of coronary heart disease codes in 24,244 participants, with 12,495 codes for incident events and 62,702 for prevalent events. Among incident event codes, 3,607 (28.87%) were for angina, 3,262 (26.11%) were for MI, 514 (4.11%) for PCTA, 161 (1.29%) for CABG and 4,951 (39.62%) were for ‘Other CHD’. Among prevalent codes, 20,254 (32.30%) were for angina, 3,644 (5.81%) for MI, 34,542 (55.09%) for ‘Other CHD’ and 4,262 (6.80%) for CABG or PCTA. Among 3,685 participants initially diagnosed exclusively with ‘Other CHD’ codes, 17.1% were recorded with angina within 5 years, 5.6% with myocardial infarction, 6.3% with CABG and 8.6% with PCTA. From 2000 to 2010, the overall incidence of CHD declined, as did the incidence of angina, but the incidence of MI did not change. The frequency of CABG declined, while PCTA increased.

Conclusion

In primary care electronic records, a substantial proportion of coronary heart disease events are recorded with codes that do not distinguish between different clinical presentations of CHD. The results draw attention to the need to improve coding practice in primary care. The results also draw attention to the importance of code selection in research studies and the need for sensitivity analyses using different sets of codes.

Within-person study designs had lower precision and greater susceptibility to bias because of trends in exposure than cohort and nested case-control designs

OBJECTIVE

To compare precision and apparent bias between cohort, nested case-control, self-controlled case series, case-crossover, and case-time-control study designs.

STUDY DESIGN AND SETTING

Study designs were implemented to evaluate the association between thiazolidinediones (TZDs) and heart failure, TZDs and fracture, and liver enzyme-inducing anticonvulsants and fracture.

RESULTS

Effect estimates were similar for the cohort and case-control study; for the association between TZDs and fracture in women, the hazard ratio was 1.36 (1.18, 1.56) and odds ratio (OR) was 1.44 (1.21, 1.70). For this clinical example, the self-controlled case series gave upward bias when follow-up was censored at the outcome (incidence rate ratio [IRR], 7.08; 4.96, 10.09) but was otherwise unbiased (IRR, 1.41; 1.14, 1.75). The retrospective case-crossover OR was 3.24 (2.18, 4.80), which was reduced by either bidirectional sampling (OR, 1.20; 0.98, 1.46) or with the case-time-control design (OR, 1.40; 1.09, 1.81). Findings on apparent bias were similar for the other two clinical examples. In each clinical example, within-person designs had considerably lower precision than the cohort or case-control study designs.

CONCLUSION

When long-term exposures are analyzed, within-person study designs may have lower precision and greater susceptibility to bias. Bias may be reduced by sampling follow-up both before and after the outcome or with the case-time-control study design.

Potential application of item-response theory to interpretation of medical codes in electronic patient records

Background

Electronic patient records are generally coded using extensive sets of codes but the significance of the utilisation of individual codes may be unclear. Item response theory (IRT) models are used to characterise the psychometric properties of items included in tests and questionnaires. This study asked whether the properties of medical codes in electronic patient records may be characterised through the application of item response theory models.

Methods

Data were provided by a cohort of 47,845 participants from 414 family practices in the UK General Practice Research Database (GPRD) with a first stroke between 1997 and 2006. Each eligible stroke code, out of a set of 202 OXMIS and Read codes, was coded as either recorded or not recorded for each participant. A two parameter IRT model was fitted using marginal maximum likelihood estimation. Estimated parameters from the model were considered to characterise each code with respect to the latent trait of stroke diagnosis. The location parameter is referred to as a calibration parameter, while the slope parameter is referred to as a discrimination parameter.

Results

There were 79,874 stroke code occurrences available for analysis. Utilisation of codes varied between family practices with intraclass correlation coefficients of up to 0.25 for the most frequently used codes. IRT analyses were restricted to 110 Read codes. Calibration and discrimination parameters were estimated for 77 (70%) codes that were endorsed for 1,942 stroke patients. Parameters were not estimated for the remaining more frequently used codes. Discrimination parameter values ranged from 0.67 to 2.78, while calibration parameters values ranged from 4.47 to 11.58. The two parameter model gave a better fit to the data than either the one- or three-parameter models. However, high chi-square values for about a fifth of the stroke codes were suggestive of poor item fit.

Conclusion

The application of item response theory models to coded electronic patient records might potentially contribute to identifying medical codes that offer poor discrimination or low calibration. This might indicate the need for improved coding sets or a requirement for improved clinical coding practice. However, in this study estimates were only obtained for a small proportion of participants and there was some evidence of poor model fit. There was also evidence of variation in the utilisation of codes between family practices raising the possibility that, in practice, properties of codes may vary for different coders.

Trends in Type 1 diabetes incidence in the UK in 0- to 14-year-olds and in 15- to 34-year-olds, 1991-2008

AIM

To describe Type 1 diabetes incidence trends in the UK between 1991 and 2008 in children aged 0-14 years and in young adults aged 15-34 years.

METHODS

Data from the UK General Practice Research Database were analysed, including 3002 individuals (1565 aged 0-14 years and 1437 aged 15-34 years) newly diagnosed with Type 1 diabetes. Poisson regression was used to model annual incidence increases and seasonality effects.

RESULTS

Type 1 diabetes incidence increased from 11 to 24/100,000 person-years in boys and from 15 to 20/100,000 person-years in girls. In adults, the incidence rate increased from 13 to 20/100,000 person-years (men) and from 7 to 10/100,000 person-years (women). Annual incidence increases tended to be greater in children (4.1%, 95% CI 3.0-5.2%) compared with 15- to 34-year-olds (2.8%, 95% CI 1.6-3.9%). There was evidence of higher incidence rates during autumn and winter in children, but not in adults.

CONCLUSIONS

A continuing increase in Type 1 diabetes incidence was shown that was greater in children than in young adults. Seasonal variation was observed in children only.

Confounder-adjusted estimates of the risk difference using propensity score-based weighting

Confounder-adjusted estimates of the risk difference are often difficult to obtain by direct regression adjustment. Estimates can be obtained from a propensity score-based method using inverse probability-of-exposure weights to balance groups defined by exposure status with respect to confounders. Simulation was used to evaluate the performance of this method. The simulation model incorporated a binary confounder and a normally distributed confounder into logistic models of exposure status, and disease status conditional on exposure status. Data were generated for combinations of values of several design parameters, including the odds ratio relating each of the confounders to exposure status, the odds ratio relating each of the confounders to disease status and the total sample size. For most design parameter combinations (474 of 486), the absolute bias in the estimated risk difference was less than 1 percentage point, and it was never greater than 3 percentage points. The confidence interval generally had close to nominal 95 per cent coverage, but was prone to poor coverage levels (as low as 78.5 per cent) when both the confounder-to-exposure and confounder-to-outcome odds ratios were 5, consistent with strong confounding. The simulation results showed that the conditions that are favourable for good performance of the weighting method are: reasonable overlap in the propensity score distributions of the exposed and non-exposed groups and a large sample size.

Income, wealth and risk of diabetes among older adults: cohort study using the English longitudinal study of ageing

BACKGROUND

Socio-economic status has been associated with diabetes in cross-sectional studies. This study aimed to evaluate associations of household income and wealth with both prevalent and incident diabetes among older adults in the UK. It also evaluated the association between obesity and socio-economic status.

METHODS

A cohort of people aged ≥50 years was selected from the English Longitudinal Study of Ageing. The relation of prevalent and incident self-reported physician diagnosed diabetes to household income and wealth was evaluated in logistic regression models adjusting for education, social class, housing tenure, age, ethnicity, marital status, body mass index (BMI), smoking, alcohol use and physical activity stratified by sex. The relation of prevalent obesity to household income and wealth was also evaluated using logistic regression models.

RESULTS

There were 9053 participants (4021 men and 5032 women) including 721 (8.0%) with diabetes at baseline. Among 8332 participants initially free from diabetes, 246 (3.0%) were diagnosed with diabetes during ∼4 years follow-up. The adjusted odds ratio for prevalent diabetes in the lowest quintile of wealth compared with the highest was 1.56 for men and 2.08 for women. Incident diabetes was associated with lower wealth (P for trend 0.05 for men and 0.004 for women) after adjusting for socio-economic and demographic factors, but attenuated after further adjustment for lifestyle and BMI. Prevalent obesity was significantly associated with lower wealth in women but not in men.

CONCLUSION

Lower wealth, but not income, may be associated with prevalent and incident diabetes among older adults in UK.

Cluster randomised trial in the General Practice Research Database: 1. Electronic decision support to reduce antibiotic prescribing in primary care (eCRT study)

Background

The purpose of this research is to develop and evaluate methods for conducting cluster randomised trials in a primary care database that contains electronic patient records for large numbers of family practices. Cluster randomised trials are trials in which the units allocated represent groups of individuals, in this case family practices and their registered patients. Cluster randomised trials often suffer from the limitation that they include too few clusters, leading to problems of insufficient power and only imprecise estimation of the intraclass correlation coefficient, a key design parameter. This difficulty might be overcome by utilising databases that already hold electronic patient records for large numbers of practices. The protocol describes one application: a study of antibiotic prescribing for acute respiratory infection; a second protocol outlines an intervention in a less frequent chronic condition of public health importance, stroke.

Methods/Design

The objective of the study is to implement a cluster randomised trial to test the effectiveness of an electronic record-based intervention at achieving a reduction in antibiotic prescribing at consultations for respiratory illness in patients aged 18 and 59 years old in intervention family practices as compared with controls. Family practices will be recruited from the practices that presently contribute data to the UK General Practice Research Database (GPRD). Following randomisation, electronic prompts will be installed remotely at intervention practices to promote adherence with evidence-based standards of medical practice. The intervention was developed through qualitative research at non-intervention practices. Data for outcome assessment will be obtained from anonymised electronic patient records that are routinely collected into GPRD. This protocol outlines the proposed study designs, data sources, sample size requirements, analysis methods and dissemination plans. Ethical issues are also discussed.

Discussion

Results from this study will provide methodological evidence concerning the use of electronic patient records and databases for implementing cluster randomised trials in primary care. The study will also provide substantive findings in respect of electronic record-based interventions to reduce antibiotic prescribing in primary care.

Trial Registration

Current Controlled Trials ISRCTN 47558792.

Place of medical qualification and outcomes of UK General Medical Council "fitness to practise" process: cohort study

OBJECTIVES

To evaluate whether country of medical qualification is associated with "higher impact" decisions at different stages of the UK General Medical Council's (GMC's) "fitness to practise" process after allowing for other characteristics of doctors and inquiries.

DESIGN

Retrospective cohort study.

SETTING

Medical practice in the United Kingdom.

PARTICIPANTS

7526 inquiries to the GMC concerning 6954 doctors.

MAIN OUTCOME MEASURES

Proportion of inquiries referred for further investigation at initial triage by the GMC, proportion of inquiries investigated that were subsequently referred for adjudication, and proportion of inquiries resulting in doctors being erased or suspended from the medical register; relative odds of higher impact decisions, by country of qualification, adjusted for doctors' sex, years since primary medical qualification, medical specialty, source and type of inquiry, and nature of allegations.

RESULTS

Of 7526 inquiries, 4702 concerned doctors who qualified in the UK, 624 concerned doctors who qualified elsewhere in the European Union (EU), and 2190 concerned doctors who qualified outside the EU. At the initial triage, 30% (n = 1398) of inquiries concerning doctors who qualified in the UK had a high impact decision, compared with 43% (267) for doctors who qualified elsewhere in the EU and 46% (998) for those who qualified outside the EU. The adjusted relative odds of an inquiry being referred for further investigation were 1.67 (95% confidence interval 1.28 to 2.17) for doctors who qualified elsewhere in the EU and 1.61 (1.38 to 1.88) for those who qualified outside the EU, compared with doctors who qualified in the UK. At the investigation stage, 5% (228) of inquiries received concerning UK qualified doctors were referred for adjudication, compared with 10% for EU (63) or non-EU (221) qualified doctors. The adjusted relative odds of referral for adjudication were 2.14 (1.46 to 3.16) for doctors who qualified elsewhere in the EU and 1.68 (1.31 to 2.16) for those who qualified outside the EU. At the adjudication stage, 1% (69) of inquiries received concerning UK qualified doctors led to erasure or suspension, compared with 4% (24) for doctors who qualified elsewhere in the EU and 3% (71) for non-EU qualified doctors. The adjusted relative odds of erasure or suspension were 2.16 (1.22 to 3.80) for doctors who qualified elsewhere in the EU and 1.48 (1.00 to 2.19) for those who qualified outside the EU.

CONCLUSIONS

Inquiries to the GMC concerning doctors qualified outside the UK are more likely to be associated with higher impact decisions at each stage of the fitness to practice process. These associations were not explained by measured inquiry related and doctor related characteristics, but residual confounding cannot be excluded.

Use of antihypertensive medications and mortality of patients with autosomal dominant polycystic kidney disease: a population-based study

BACKGROUND

This study aimed to estimate the association between antihypertensive therapy and mortality in patients with autosomal dominant polycystic kidney disease (ADPKD).

STUDY DESIGN

Cohort study.

SETTING & PARTICIPANTS

Participants with ADPKD from the UK General Practice Research Database older than 15 years between 1991 and 2008.

PREDICTORS

Use of 5 major classes of antihypertensive drug.

OUTCOMES

Deaths, new renal replacement therapy events.

MEASUREMENTS

Random-effects Poisson models were adjusted for age, sex, year of entry into the cohort, calendar year, prevalent coronary heart disease, stroke, diabetes, hyperlipidemia, and lipid-lowering therapy.

RESULTS

From 1991-2008, there were 2,085 cases of ADPKD, with 1,877 contributing person-time for ages older than 15 years. In 1991, antihypertensive drugs were not prescribed for 68% of participants, which decreased to 38% by 2008. The proportion for which 1 class of antihypertensive drug was prescribed increased from 19% in 1991 to 24% in 2008; 2 classes, from 11% to 22%; 3 classes, from 2% to 11%; and 4 or 5 classes, from 1% to 5%. In 1991, drugs acting on the renin-angiotensin system were prescribed for only 7% of participants; by 2008, this had increased to 46%. There was evidence of a trend toward decreasing mortality as the number of antihypertensive drug classes prescribed in a year increased. For participants with 3 classes of drugs prescribed, the incident rate ratio was 0.11 (95% CI, 0.05-0.21; P < 0.001). Each annual increment in year of entry into the cohort was associated with a 6% (95% CI, 2%-10%; P = 0.008) decrease in mortality.

LIMITATIONS

Reported associations might be accounted for by unmeasured or incompletely measured confounders. These might include changes in other aspects of medical care for patients with ADPKD.

CONCLUSION

Increasing coverage and intensity of antihypertensive therapy is associated with decreasing mortality in people with ADPKD.

Utility of electronic patient records in primary care for stroke secondary prevention trials

BACKGROUND

This study aimed to inform the design of a pragmatic trial of stroke prevention in primary care by evaluating data recorded in electronic patient records (EPRs) as potential outcome measures. The study also evaluated achievement of recommended standards of care; variation between family practices; and changes in risk factor values from before to after stroke.

METHODS

Data from the UK General Practice Research Database (GPRD) were analysed for 22,730 participants with an index first stroke between 2003 and 2006 from 414 family practices. For each subject, the EPR was evaluated for the 12 months before and after stroke. Measures relevant to stroke secondary prevention were analysed including blood pressure (BP), cholesterol, smoking, alcohol use, body mass index (BMI), atrial fibrillation, utilisation of antihypertensive, antiplatelet and cholesterol lowering drugs. Intraclass correlation coefficients (ICC) were estimated by family practice. Random effects models were fitted to evaluate changes in risk factor values over time.

RESULTS

In the 12 months following stroke, BP was recorded for 90%, cholesterol for 70% and body mass index (BMI) for 47%. ICCs by family practice ranged from 0.02 for BP and BMI to 0.05 for LDL and HDL cholesterol. For subjects with records available both before and after stroke, the mean reductions from before to after stroke were: mean systolic BP, 6.02 mm Hg; diastolic BP, 2.78 mm Hg; total cholesterol, 0.60 mmol/l; BMI, 0.34 Kg/m2. There was an absolute reduction in smokers of 5% and heavy drinkers of 4%. The proportion of stroke patients within the recommended guidelines varied from less than a third (29%) for systolic BP, just over half for BMI (54%), and over 90% (92%) on alcohol consumption.

CONCLUSIONS

Electronic patient records have potential for evaluation of outcomes in pragmatic trials of stroke secondary prevention. Stroke prevention interventions in primary care remain suboptimal but important reductions in vascular risk factor values were observed following stroke. Better recording of lifestyle factors in the GPRD has the potential to expand the scope of the GPRD for health care research and practice.

Increasing socio-economic inequality in type 2 diabetes prevalence--repeated cross-sectional surveys in England 1994-2006

BACKGROUND

This study aimed to evaluate the association of rising type 2 diabetes prevalence with socio-economic inequality in diabetes.

METHODS

Data from the Health Survey for England were analysed for 1994, 1998, 2003 and 2006. This is a nationally representative annual survey of private households. Data for 41,643 individuals aged ≥35 years were included. The prevalence of self-reported diabetes diagnosed by a doctor was analysed in relation to household income, occupational social class and educational qualifications. Data were standardized for age using the European Standard Population for reference.

RESULTS

Prevalence of diagnosed diabetes increased in men from 3.74% in 1994 to 7.25% in 2006, and in women from 2.28% to 4.88%. In 1994, there were no associations between social class or educational level and diabetes prevalence evident. In 2006, there was evidence of a negative association in women [prevalence ratio for social class (IV + V vs. I) = 4.54, P-value for trend = 0.005; prevalence ratio for educational level ('none' vs. 'A-levels') = 1.96, P-value for trend = 0.001]. The Slope Index of Inequality (SII) for social class in women increased from -1.65 in 1994 to -4.95 [95% Confidence Interval (95% CI -8.52 to -1.38)] in 2006 and for level of education from -1.39 to -6.48 (95% CI -9.03 to -3.93). In men, diabetes prevalence was not associated with social class or level of education.

CONCLUSION

Increasing prevalence of type 2 diabetes has been associated with an increase of socio-economic inequality in women. There was no socio-economic gradient observed in men.

Family practices' achievement of diabetes quality of care targets and risk of screen-detected diabetic retinopathy

BACKGROUND

We aimed to determine whether family practices' achievement of diabetes quality of care targets is associated with diabetic retinal disease in registered patients.

METHODS

Data for achievement of diabetes quality of care targets, including the proportion of patients with HbA1c < or = 7.5%, for 144 family practices in London UK, for the years 2004/5 to 2007/8, were linked to data from a population-based diabetes eye screening programme collected from September 2007 to February 2009. Analyses were adjusted for age, sex, duration and type of diabetes, unadjusted diabetes prevalence, ethnicity and deprivation category.

RESULTS

Data were analysed for 24,458 participants with one or more eye screening results in the period. There were 9,332 (38%) with any diabetic retinopathy and 2,819 (11.5%) with sight threatening diabetic retinopathy (STDR), including 2,654 (10.9%) with maculopathy. Among participants registered at 13 family practices that were in the highest quartile for achievement of the HbA1c quality of care target for all four years of study, the relative odds of any diabetic retinopathy were 0.78 (0.69 to 0.88) P<0.001. For participants at 12 practices consistently in the lowest quartile of HbA1c achievement, the relative odds of any diabetic retinopathy were 1.16 (1.03 to 1.30), P = 0.015. In the highest achieving practices, the relative odds of maculopathy were 0.74 (0.62 to 0.89), P = 0.001 and STDR 0.77 (0.65 to 0.92), P = 0.004.

CONCLUSIONS

The risk of diabetic retinopathy might be lower at family practices that consistently achieve highly on diabetes quality of care targets for HbA1c.